1 /* 2 * Based on arch/arm/include/asm/uaccess.h 3 * 4 * Copyright (C) 2012 ARM Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 #ifndef __ASM_UACCESS_H 19 #define __ASM_UACCESS_H 20 21 #include <asm/alternative.h> 22 #include <asm/kernel-pgtable.h> 23 #include <asm/sysreg.h> 24 25 /* 26 * User space memory access functions 27 */ 28 #include <linux/bitops.h> 29 #include <linux/kasan-checks.h> 30 #include <linux/string.h> 31 32 #include <asm/cpufeature.h> 33 #include <asm/ptrace.h> 34 #include <asm/memory.h> 35 #include <asm/compiler.h> 36 #include <asm/extable.h> 37 38 #define KERNEL_DS (-1UL) 39 #define get_ds() (KERNEL_DS) 40 41 #define USER_DS TASK_SIZE_64 42 #define get_fs() (current_thread_info()->addr_limit) 43 44 static inline void set_fs(mm_segment_t fs) 45 { 46 current_thread_info()->addr_limit = fs; 47 48 /* On user-mode return, check fs is correct */ 49 set_thread_flag(TIF_FSCHECK); 50 51 /* 52 * Enable/disable UAO so that copy_to_user() etc can access 53 * kernel memory with the unprivileged instructions. 54 */ 55 if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS) 56 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO)); 57 else 58 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO, 59 CONFIG_ARM64_UAO)); 60 } 61 62 #define segment_eq(a, b) ((a) == (b)) 63 64 /* 65 * Test whether a block of memory is a valid user space address. 66 * Returns 1 if the range is valid, 0 otherwise. 67 * 68 * This is equivalent to the following test: 69 * (u65)addr + (u65)size <= current->addr_limit 70 * 71 * This needs 65-bit arithmetic. 72 */ 73 #define __range_ok(addr, size) \ 74 ({ \ 75 unsigned long __addr = (unsigned long)(addr); \ 76 unsigned long flag, roksum; \ 77 __chk_user_ptr(addr); \ 78 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 79 : "=&r" (flag), "=&r" (roksum) \ 80 : "1" (__addr), "Ir" (size), \ 81 "r" (current_thread_info()->addr_limit) \ 82 : "cc"); \ 83 flag; \ 84 }) 85 86 /* 87 * When dealing with data aborts, watchpoints, or instruction traps we may end 88 * up with a tagged userland pointer. Clear the tag to get a sane pointer to 89 * pass on to access_ok(), for instance. 90 */ 91 #define untagged_addr(addr) sign_extend64(addr, 55) 92 93 #define access_ok(type, addr, size) __range_ok(addr, size) 94 #define user_addr_max get_fs 95 96 #define _ASM_EXTABLE(from, to) \ 97 " .pushsection __ex_table, \"a\"\n" \ 98 " .align 3\n" \ 99 " .long (" #from " - .), (" #to " - .)\n" \ 100 " .popsection\n" 101 102 /* 103 * User access enabling/disabling. 104 */ 105 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 106 static inline void __uaccess_ttbr0_disable(void) 107 { 108 unsigned long ttbr; 109 110 /* reserved_ttbr0 placed at the end of swapper_pg_dir */ 111 ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE; 112 write_sysreg(ttbr, ttbr0_el1); 113 isb(); 114 } 115 116 static inline void __uaccess_ttbr0_enable(void) 117 { 118 unsigned long flags; 119 120 /* 121 * Disable interrupts to avoid preemption between reading the 'ttbr0' 122 * variable and the MSR. A context switch could trigger an ASID 123 * roll-over and an update of 'ttbr0'. 124 */ 125 local_irq_save(flags); 126 write_sysreg(current_thread_info()->ttbr0, ttbr0_el1); 127 isb(); 128 local_irq_restore(flags); 129 } 130 131 static inline bool uaccess_ttbr0_disable(void) 132 { 133 if (!system_uses_ttbr0_pan()) 134 return false; 135 __uaccess_ttbr0_disable(); 136 return true; 137 } 138 139 static inline bool uaccess_ttbr0_enable(void) 140 { 141 if (!system_uses_ttbr0_pan()) 142 return false; 143 __uaccess_ttbr0_enable(); 144 return true; 145 } 146 #else 147 static inline bool uaccess_ttbr0_disable(void) 148 { 149 return false; 150 } 151 152 static inline bool uaccess_ttbr0_enable(void) 153 { 154 return false; 155 } 156 #endif 157 158 #define __uaccess_disable(alt) \ 159 do { \ 160 if (!uaccess_ttbr0_disable()) \ 161 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ 162 CONFIG_ARM64_PAN)); \ 163 } while (0) 164 165 #define __uaccess_enable(alt) \ 166 do { \ 167 if (!uaccess_ttbr0_enable()) \ 168 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ 169 CONFIG_ARM64_PAN)); \ 170 } while (0) 171 172 static inline void uaccess_disable(void) 173 { 174 __uaccess_disable(ARM64_HAS_PAN); 175 } 176 177 static inline void uaccess_enable(void) 178 { 179 __uaccess_enable(ARM64_HAS_PAN); 180 } 181 182 /* 183 * These functions are no-ops when UAO is present. 184 */ 185 static inline void uaccess_disable_not_uao(void) 186 { 187 __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); 188 } 189 190 static inline void uaccess_enable_not_uao(void) 191 { 192 __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); 193 } 194 195 /* 196 * The "__xxx" versions of the user access functions do not verify the address 197 * space - it must have been done previously with a separate "access_ok()" 198 * call. 199 * 200 * The "__xxx_error" versions set the third argument to -EFAULT if an error 201 * occurs, and leave it unchanged on success. 202 */ 203 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 204 asm volatile( \ 205 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 206 alt_instr " " reg "1, [%2]\n", feature) \ 207 "2:\n" \ 208 " .section .fixup, \"ax\"\n" \ 209 " .align 2\n" \ 210 "3: mov %w0, %3\n" \ 211 " mov %1, #0\n" \ 212 " b 2b\n" \ 213 " .previous\n" \ 214 _ASM_EXTABLE(1b, 3b) \ 215 : "+r" (err), "=&r" (x) \ 216 : "r" (addr), "i" (-EFAULT)) 217 218 #define __get_user_err(x, ptr, err) \ 219 do { \ 220 unsigned long __gu_val; \ 221 __chk_user_ptr(ptr); \ 222 uaccess_enable_not_uao(); \ 223 switch (sizeof(*(ptr))) { \ 224 case 1: \ 225 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 226 (err), ARM64_HAS_UAO); \ 227 break; \ 228 case 2: \ 229 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 230 (err), ARM64_HAS_UAO); \ 231 break; \ 232 case 4: \ 233 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 234 (err), ARM64_HAS_UAO); \ 235 break; \ 236 case 8: \ 237 __get_user_asm("ldr", "ldtr", "%x", __gu_val, (ptr), \ 238 (err), ARM64_HAS_UAO); \ 239 break; \ 240 default: \ 241 BUILD_BUG(); \ 242 } \ 243 uaccess_disable_not_uao(); \ 244 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 245 } while (0) 246 247 #define __get_user(x, ptr) \ 248 ({ \ 249 int __gu_err = 0; \ 250 __get_user_err((x), (ptr), __gu_err); \ 251 __gu_err; \ 252 }) 253 254 #define __get_user_error(x, ptr, err) \ 255 ({ \ 256 __get_user_err((x), (ptr), (err)); \ 257 (void)0; \ 258 }) 259 260 #define get_user(x, ptr) \ 261 ({ \ 262 __typeof__(*(ptr)) __user *__p = (ptr); \ 263 might_fault(); \ 264 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 265 __get_user((x), __p) : \ 266 ((x) = 0, -EFAULT); \ 267 }) 268 269 #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 270 asm volatile( \ 271 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 272 alt_instr " " reg "1, [%2]\n", feature) \ 273 "2:\n" \ 274 " .section .fixup,\"ax\"\n" \ 275 " .align 2\n" \ 276 "3: mov %w0, %3\n" \ 277 " b 2b\n" \ 278 " .previous\n" \ 279 _ASM_EXTABLE(1b, 3b) \ 280 : "+r" (err) \ 281 : "r" (x), "r" (addr), "i" (-EFAULT)) 282 283 #define __put_user_err(x, ptr, err) \ 284 do { \ 285 __typeof__(*(ptr)) __pu_val = (x); \ 286 __chk_user_ptr(ptr); \ 287 uaccess_enable_not_uao(); \ 288 switch (sizeof(*(ptr))) { \ 289 case 1: \ 290 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 291 (err), ARM64_HAS_UAO); \ 292 break; \ 293 case 2: \ 294 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 295 (err), ARM64_HAS_UAO); \ 296 break; \ 297 case 4: \ 298 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 299 (err), ARM64_HAS_UAO); \ 300 break; \ 301 case 8: \ 302 __put_user_asm("str", "sttr", "%x", __pu_val, (ptr), \ 303 (err), ARM64_HAS_UAO); \ 304 break; \ 305 default: \ 306 BUILD_BUG(); \ 307 } \ 308 uaccess_disable_not_uao(); \ 309 } while (0) 310 311 #define __put_user(x, ptr) \ 312 ({ \ 313 int __pu_err = 0; \ 314 __put_user_err((x), (ptr), __pu_err); \ 315 __pu_err; \ 316 }) 317 318 #define __put_user_error(x, ptr, err) \ 319 ({ \ 320 __put_user_err((x), (ptr), (err)); \ 321 (void)0; \ 322 }) 323 324 #define put_user(x, ptr) \ 325 ({ \ 326 __typeof__(*(ptr)) __user *__p = (ptr); \ 327 might_fault(); \ 328 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 329 __put_user((x), __p) : \ 330 -EFAULT; \ 331 }) 332 333 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 334 #define raw_copy_from_user __arch_copy_from_user 335 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 336 #define raw_copy_to_user __arch_copy_to_user 337 extern unsigned long __must_check raw_copy_in_user(void __user *to, const void __user *from, unsigned long n); 338 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 339 #define INLINE_COPY_TO_USER 340 #define INLINE_COPY_FROM_USER 341 342 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 343 { 344 if (access_ok(VERIFY_WRITE, to, n)) 345 n = __clear_user(to, n); 346 return n; 347 } 348 349 extern long strncpy_from_user(char *dest, const char __user *src, long count); 350 351 extern __must_check long strnlen_user(const char __user *str, long n); 352 353 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 354 struct page; 355 void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len); 356 extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n); 357 358 static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) 359 { 360 kasan_check_write(dst, size); 361 return __copy_user_flushcache(dst, src, size); 362 } 363 #endif 364 365 #endif /* __ASM_UACCESS_H */ 366